Experiment Study And Simulation Analysis On Clearance Characteristics In Shearing Process Of Three-body Friction Interface

The present paper constructed experiment equipment which can realize the shearing process of three-body friction interface. The device can test effectively the clearance of shearing of three-body friction interface. A series of tests were conducted which concern the influence of normal load, shear velocity and particle diameter on the clearance of the three-body friction interface. The experimental results indicate that the relationship between clearance characteristic and load is different due to the difference of particle size. In the range of test conditions, load affects the clearance weakly and the stability is the best under particle1#. The trend of clearance becomes larger after decrease first, and decreases at last with load getting lager under particle2#. For the particle3#, there exist no obvious difference of clearance under different load except the value of7500Pa, but it is distinct lager under the load of7500Pa than the others, and the stability is the worst except the load of10000Pa. The value of clearance increases with the increase of particle diameter, while the degree of shear dilatancy decreases and the stability of clearance gets worse. With shear velocity increasing, the variation of clearance appears a trend of reducing under high shear velocity after increasing under low shear velocity, the influence of shear velocity on clearance stability under the light normal load is more obvious than the heavy.Due to the complexity of three-body friction interface, it’s difficult to observe the third bodies’behavior, such as the stress, micro-movement and so on. Therefore, for simulating the infinite length shear process of the interface, a finite element model of three-body friction interface was established in present paper. The simulation results show that the shear dilatancy phenomenon is the result of "climb-over" between particles of different layer, meanwhile, uplift force generates in the interface because of the shear behavior and is relate to normal load, shear velocity, particle’s friction coefficient, particle size and material. The shear clearance decreases with normal load increasing in the whole, but there still exist the contrary situation in local. The variation trend of shear clearance with shear velocity increasing is similar to a reversed "W". ihe shear clearance increases with particle size getting lager, but shear dilatancy present an opposite variation trend. There is a positive correlation between shear clearance and particle’s friction coefficient. The shear clearance reduce with the material hardness of particle decreasing except the graphite particle, and it is much larger with graphite particles than the others material particles. It appears diversity of the slide-roll phenomenon, stress and force chain of particles during the shearing process, which is the primary reason of leading to the difference of uplift force and shear clearance.